1. Field of the Disclosure
The present invention relates to a method and a system for assessing a level of dyspnea in a patient.
2. Description of the Related Art
Chronic Obstructive Pulmonary Disease (COPD) is a respiratory disease that is characterized by inflammation of the airways. It is characterized by an airflow limitation that is typically not fully reversible. The airflow limitation is both progressive and associated with an abnormal inflammatory response of the lungs to noxious particles or gases. Symptoms of COPD may include coughing, wheezing, dyspnea (i.e., shortness of breath or breathlessness), and the production of mucus and the degree of severity may, in part, be viewed in terms of the volume and color of secretions.
Dyspnea (i.e., shortness of breath or breathlessness) is one the most common symptom for COPD or Heart Failure (HF) patients. The worsening of dyspnea is an important indicator for the deterioration of health status of COPD or HF patient. Therefore, measurement of dyspnea provides valuable information for assessing the health status of COPD or HF patient.
Currently, dyspnea is measured using questionnaires. One such (most widely used) questionnaire is the Medical Research Council (MRC) questionnaire. The MRC questionnaire, which is shown in Table 1 below, is a five point scale questionnaire that allows patients to indicate the extent to which their breathlessness affects their daily activities. However, the MRC questionnaire does not quantify breathlessness itself and only provides a measure of perception of dyspnea by the patient. The perception of dyspnea is variable from patient to patient, as some patients may underestimate their level of dyspnea while other patients may overestimate their level of dyspnea.
TABLE 1MRC questionnaireScaleSeverity1Breathless with strenuous exercise2Short of breath when hurrying on the level surface or walkingup a slight hill3Walks slower than people of the same age on a level surfacebecause of breathlessness of I have to stop or I have to stop forbreath when walking at my own pace on the level surface4Stops for breath after walking for 100 meters or a few minuteson a level surface5Too breathless to leave the house or I am breathless dressing andundressing
Further, the questionnaire based assessments, such as one used for dyspnea, are subjective and rely on memory recall, which is especially difficult for the elderly. Also, the questionnaire based assessments, such as one used for dyspnea, are designed to be short (i.e., with specific questions/statements) to ensure compliance, but such short questionnaires may lack sensitivity to detect changes in the level of dyspnea. Furthermore, the questionnaire based assessments, such as one used for dyspnea, are unable to provide an accurate assessment of dyspnea, as these questionnaires do not account for a modification in behavior of the patient (e.g., patient may walk less to avoid getting breathless) and variation in effort provided by the patient (e.g., slow walking vs. fast walking).